graves



(No Model.)

J. B. GRAVES.

DENTAL UD No. 270,566. Patented Jan.9, 1883.

W/ T/VESSES I y ymp iAf f or ey UNTTED STATES PATENT Trice.

JOHN B. GRAVES, OF LEBANON, TENNESSEE, ASSIGNOR OF ONE-HALF TO WILLIAMH. BENNETT, OF SAME PLACE.

DENTAL MODEL.

SPECIFICATION forming part of Letters Application filed August 10, 1882.

To all whom it may concern:

Be it known that 1, JOHN B. GRAVES, of Lebanon, in the county of Wilsonand State of Tennessee, have invented certain new and usefulImprovements in Dental Models; and I do hereby declare the following tobe at'ull, clear, and exact description of the invention, such as willenable others skilled in the art to which it pertains to make and usethe same.

My invention relates to metallic dental models, and to processes forforming the same.

Heretofore metallic models on which to swage metallic plates. or moldplates from plastic material, to serve as bases for artificial teeth orI5 palatine obturators, have been cast solid in one piece. In mostinstancesthere are under-cuts on such models, produced in casting thelatter by protrusions or fullness of the alveolar arches, which renderit impossible to remove a plate formed upon the model without changingthe shape of the plate by bending, and thus impairing it.

The object of my invention is to obviate the objection above poted byforming the model in sections, whereby it may be removed from the platewithout bending or impairing the latter.

The invention consists in the process and devices hereinafter fullydescribed, and pointed 0 out in the claims.

In the drawings, Figure 1 is a perspective view of an impression takenfrom the mouth and filled with wax and a central core ofplaster-of-paris. Fig. 2 is a transverse vertical section of Fig. 1.Fig. 3 represents the impression surrounded by paper. Fig. 4 representsa perspective view of the section-plate and retainers, and Fig. 5 is areverse plan view of the completed model secured to the support- 0ing-plate. Fig. 6 is'a transverse vertical section of Fig. 5.

My improved model is formed in the following manner: Take an impression,A, of the mouth, in wax or other suitable material, in the 5 usual way.The-inner or top portion of the impression is then coated with varnishor soap to prevent the adherence of the plaster thereto. Fill in thecavities at the sides of the impression-with wax fillings B, whichshould be cut away on their inner edges to form inclined or beveledsides b, and the space between the two Patent No. 270,566, dated January9, 1883.

(No model.)

| opposite wax fillings should be wider at the back than at the front ofthe impression, and closed temporarily at its back end by a piece of waxto form a receptacle or mold for a central core, 0, of plaster. Theinnersides of the wax fillings should be oiled to prevent the adherencethereto of the central core, which is poured into the space between thewax fillings and allowed to set. After said central core is sufficientlyhardened and set the wax fillings are removed from the impression A; Thelatter, with the central core in place, is then wrapped with paper orother equivalent material to form an outer flange, 1), for the impression, extending sufficiently above the latter to insure the properthickness of the metallic model.

E represents a supporting-plate, which I term a section-plate. It isprovided with a central opening, 0, and a central bar or retainer, F,having depending pinsf, adapted to enter perforationsf of the plate, andsecured to the plate by screws f passing through the plate and intoscrew-threaded perforations)" of the retainer.

On. each side of the plate E is removably secured a retainer, G,provided with depending lugs or pins g, adapted to enter holes g of theplate, and a threaded perforation, 9 to receive a screw, 9 to secure theretainer to the plate. The outer sides of these retainers G arepreferably curved or rounded to correspond'to the curvature of theplate.

After the paper has been applied to the impression A, as aboveexplained, and as shown in Fig. 3, the central retainer, F, is removedfrom the plate E, and the latter is applied to the impression A, theside retainers, G G, projecting into the spaces previously occupied bythe wax fillings, but not extending to the surface of the impression.Molten metal is then poured into said spaces through the centralopening, e, of the plate E, on each side of the central core, 0, and themetal' will be cast 5 around the retainers G G to form the sides H H ofthe model. The screws are then removed to allow the section-plate to beremoved. The central retainer is then secured to the plate. The plastercore 0 is then removed. and the plate E is placed upon the sideretainers and screwed thereto, the central retainer pro- IOO jectinginto the space previously occupied by the core 0. Molten metal is thenpoured into said space through the opening in the plate to form thecentral section, I, of the model, which will be cast around the centralretainer. The plate E is then removed, with the model-sections securedthereto, and the model is completed and ready for use. The plate for theteeth is formed by swaging it upon the model, it'theplateis of metal orby molding,iftheplate is to be made from plastic material. After theplate thus formed is ready to be removed from the model thesupporting-plate E of the latter removed by removing the screws whichsecure it. The central section, I, is removed from the completed plate,and afterward the side sections, H H.

It will be apparent that with a model constructed in the manner thusdescribed a pert'ect plate may be obtained, as the model may be removedwithout bending or injuring the plate. \Vhen it is desired to again usethe section-plate and retainers the model-sections are melted off of theretainers, and the device is ready for a repetition of theabove-described process.

It is evidentthatmany slight deviations may i be made from theconstruction of the devices above described. Hence I would have itunderstood that I do not limit myself to the precise arrangement andconstruction above set forth, but reserve to myself the right to makesuch changes and alterations as may properly fall within the scope of myinvention.

Having fully described myinvention, what I claim as new, and desire to,secure by Letters Patent, is-- 1. A process for forming dentalmodels,consisting in first taking an impression of the month, thenfilling the cavities at the sides of 0 the impression with wax andforming a. central core of plaster, removing said fillings in the mannerdescribed, and casting the model in sections around bars or retainers,which latter are secured removably to a supportingplate, substantiallyas set forth.

2. A process for forming dental models, consisting in first taking animpression of the month, then filling the sides of said impression withwax, casting a central core of plaster-ofparis, or equivalent material,between said fillings, then removing the latter and surrounding theimpression with paper or other material, and applying to the impressiona sectionplate having a central and side retainers, casting the sidesections of the model, then removing the central core and casting thecentral model-section, substantially as set forth.

3. As a new article of manufacture, a dental model consisting ofindependent sections cast upon retainers, which latter are removablysecured to a supporting plate, substantially as set forth.

4. The combination, with the supportingplate provided with a centralaperture, of the retainers G G and F, removably secured to the plate,substantially as set forth.

In testimony whereot'I have signed this specification in the presence oftwo subscribing witnesses.

JOHN B. GRAVES. \Vitnesses:

ALEX. W. VICK, T. H. EATIIERLY.

